How to Cut Concrete Backer Board

cutting backer board
  • 1 hours
  • Beginner
  • 7-10
What You'll Need
Utility knife
Straight edge
Tape measure
Dust mask
Safety glasses

A concrete backer board is an essential component for building a bathroom or shower. It's a type of drywall that is used with a moisture barrier to prevent the studs from rotting due to the excessive moisture from the shower. It is used in shower walls, bathtub sub-flooring, and bathroom flooring.

The material in a concrete backer board is harder than gypsum sheet-rock drywall. Although it is cut in a similar manner, cutting a concrete backer board requires the following tools and steps in order to successfully cut to size the piece that you need.

Put on Safety Equipment

Wear safety glasses when cutting the concrete backer board to protect your eyes from debris. Because the blade that you will be using is extremely sharp, you should also wear safety gloves to protect your hands. A dust mask will keep any loose debris in the air from getting in your lungs.

Measure the Area for the Concrete Backer Board

Measure the area where the concrete backer board will be attached. Use a pencil to mark the paper side to indicate where cuts need to be made. Check your measurements carefully for accuracy.

Score the Backer Board

Align a straight edge against the pencil marking and score a mark across the concrete backer board with a utility knife. Unlike dealing with gypsum board, which can be scored with a regular utility knife, you will need a special carbide-bladed utility knife to score the concrete backer board. Run the knife across the board several times.

Remove the straight edge and run the blade across your marking several times, using pressure to make the cut deep. Doing so will give you a cleaner break when you tear the measured piece away from the rest of the concrete backer board.

Snap the Concrete Backer Board

Position the concrete backer board against a worktable with the scoreline out a bit. Hit the backer board with the palm of your hand. It should give way, breaking the desired piece. You may need to hit the concrete backer board several times in order for it to break away cleanly.

You can use the carbide blade to clean up any remaining piece of the concrete backer board from the cut piece. Once you have done so, you should have a clean piece ready to be affixed to the wall.??

It may take some practice when working with a concrete backer board to make your score lines and cuts clean, but it should become easier for you. Practice with a small scrap piece in order to get a sense of how the concrete backer board feels before making your cuts.